[PATCH] D57600: update docs of memcpy/memmove/memset re: alignment and len=0
Ralf via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 26 03:28:37 PST 2019
RalfJung updated this revision to Diff 188333.
RalfJung added a comment.
Fix typo.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D57600/new/
https://reviews.llvm.org/D57600
Files:
llvm/docs/LangRef.rst
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -1071,10 +1071,11 @@
``align <n>``
This indicates that the pointer value may be assumed by the optimizer to
- have the specified alignment.
+ have the specified alignment. If the pointer value does not have the
+ specified alignment, behavior is undefined.
Note that this attribute has additional semantics when combined with the
- ``byval`` attribute.
+ ``byval`` attribute, which are documented there.
.. _noalias:
@@ -11234,8 +11235,11 @@
The '``llvm.memcpy.*``' intrinsics copy a block of memory from the
source location to the destination location, which are not allowed to
overlap. It copies "len" bytes of memory over. If the argument is known
-to be aligned to some boundary, this can be specified as the fourth
-argument, otherwise it should be set to 0 or 1 (both meaning no alignment).
+to be aligned to some boundary, this can be specified as an attribute on
+the argument.
+
+If "len" is 0, the pointers may be NULL or dangling. However, they must still
+be appropriately aligned.
.. _int_memmove:
@@ -11289,8 +11293,11 @@
The '``llvm.memmove.*``' intrinsics copy a block of memory from the
source location to the destination location, which may overlap. It
copies "len" bytes of memory over. If the argument is known to be
-aligned to some boundary, this can be specified as the fourth argument,
-otherwise it should be set to 0 or 1 (both meaning no alignment).
+aligned to some boundary, this can be specified as an attribute on
+the argument.
+
+If "len" is 0, the pointers may be NULL or dangling. However, they must still
+be appropriately aligned.
.. _int_memset:
@@ -11340,7 +11347,12 @@
""""""""""
The '``llvm.memset.*``' intrinsics fill "len" bytes of memory starting
-at the destination location.
+at the destination location. If the argument is known to be
+aligned to some boundary, this can be specified as an attribute on
+the argument.
+
+If "len" is 0, the pointers may be NULL or dangling. However, they must still
+be appropriately aligned.
'``llvm.sqrt.*``' Intrinsic
^^^^^^^^^^^^^^^^^^^^^^^^^^^
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